Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7732186 | Journal of Power Sources | 2015 | 8 Pages |
Abstract
This paper introduces a novel, efficient method for the synthesis of TiOF2, and outlines the mechanisms of TiOF2 on discharge (reduction) and charge (oxidation). Anatase TiO2 is reacted with hydrofluoric acid, HF, to produce TiOF2. The synthesized TiOF2 is crystallized into a cubic perovskite structure with a Pm3m space group, as confirmed by Rietveld refinement of X-ray diffraction data. The particles show peculiar cubic-shaped secondary particle morphology. Electrochemical investigation indicated that the TiOF2 delivers a high charge capacity 526 mAh gâ1. X-ray diffraction, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and transmission electron microscopy are employed to elucidate the reaction process. During lithiation, TiOF2 adopts Li+ ions into the cubic perovskite structure to form LiTiOF2, and the phase separates to LiF and TiO by further lithiation. The formed TiO is oxidized to TiO2 during charging although those oxides are in an amorphous state. The electrochemical reaction seems to be fairly stable, retaining 94.5% of its capacity during 100 cycles, starting from the second cycle. Also, the electrode is suitable for operation at high rates, namely, 400 mAh gâ1 at 200 mA gâ1, 345 mAh gâ1 at 1.6 A gâ1, and 288 mAh gâ1 at 3.2 A gâ1.
Related Topics
Physical Sciences and Engineering
Chemistry
Electrochemistry
Authors
Seung-Taek Myung, Masaru Kikuchi, Chong Seung Yoon, Hitoshi Yashiro, Yang-Kook Sun,